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Engine Mount Control System (4-CYL): Troubleshooting

Special Tools Required 

Vacuum pump/gauge, 0-30 in.Hg

Snap-on YA4000A or equivalent, commercially available

NOTE: Check the vacuum hoses and lines for damage and proper connections before troubleshooting.

Follow this procedure if the engine vibrates excessively when idling

  1. Connect the Honda Diagnostic System (HDS) to the data link connector (DLC) (see step 2 on GENERAL TROUBLESHOOTING INFORMATION ).
  2. Turn the ignition switch to ON (II).
  3. Make sure the HDS communicates with the vehicle and the engine control module (ECM)/powertrain control module (PCM) If it doesn't communicate, troubleshoot the DLC circuit (see DLC CIRCUIT TROUBLESHOOTING ).
  4. Check the idle speed (see IDLE SPEED INSPECTION ).
  5. Raise the engine speed from idling to 2,000 rpm.
  6. Check the MOUNT CTRL SOL in the PGM-FI DATA LIST with the Honda Diagnostic System (HDS)

    Is ON indicated at idling and OFF indicated at 2,000 rpm? 

    YES  -Go to step 7.

    NO  -Update the ECM/PCM if it does not have the latest software (see ECM/PCM UPDATE ), or substitute a known-good ECM/PCM (see SUBSTITUTING THE ECM/PCM ), then recheck. If the engine mount control system works properly, and the ECM/PCM was updated, the troubleshooting is complete. If the ECM/PCM was substituted, replace the original ECM/PCM (see ECM/PCM REPLACEMENT ).

  7. Turn the ignition switch to LOCK (0).
  8. Disconnect the engine mount control solenoid valve 2P connector from the engine mount control solenoid valve.
  9. Turn the ignition switch to ON (II).
  10. Measure the voltage between engine mount control solenoid valve 2P connector terminal No. 2 and body ground.
    Fig 1: Measuring Voltage Between Engine Mount Control Solenoid Valve 2P Connector Terminal 2 And Body Ground
    G05991730Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there battery voltage? 

    YES  -Go to step 11.

    NO  -Repair open in the wire between engine mount control solenoid valve 2P connector terminal No 2 and No 7 (15 A) fuse in the driver's under-dash fuse/relay box

  11. Start the engine, and let it idle.
  12. Measure the voltage between engine mount control solenoid valve 2P connector terminals No. 1 and No 2 with the engine at idle.
    Fig 2: Measuring Voltage Between Engine Mount Control Solenoid Valve 2P Connector Terminals 1 And 2
    G05991731Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there battery voltage? 

    YES  -Go to step 13

    NO  -Repair open in the wire between ECM/PCM (C40) and the engine mount control solenoid valve 2P connector. If the wire is OK, update the ECM/PCM if it does not have the latest software (see ECM/PCM UPDATE ), or substitute a known-good ECM/PCM (see THE ECM/PCM ), and recheck. If the engine mount control system works properly, and the ECM/PCM was updated, the troubleshooting is complete If the ECM/PCM was substituted, replace the original ECM/PCM (see ECM/PCM REPLACEMENT )

  13. Raise the engine speed above 1,000 rpm.
  14. Measure the voltage between engine mount control solenoid valve 2P connector terminals No. 1 and No. 2
    Fig 3: Measuring Voltage Between Engine Mount Control Solenoid Valve 2P Connector Terminals 1 And 2
    G05991732Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there battery voltage? 

    YES  -Repair short to body ground in the wire between ECM/PCM (C40) and the engine mount control solenoid valve. If the wire is OK, update the ECM/PCM if it does not have the latest software (see ECM/PCM UPDATE ), or substitute a known-good ECM/PCM (see SUBSTITUTING THE ECM/PCM ), and recheck. If the engine mount control system works properly, and the ECM/PCM was updated, the troubleshooting is complete. If the ECM/PCM was substituted, replace the original ECM/PCM (see ECM/PCM REPLACEMENT )

    NO  -Go to step 15

  15. Turn the ignition switch to LOCK (0).
  16. Disconnect the upper vacuum hose (A) from the engine mount control solenoid valve (B), and connect a vacuum pump/gauge, 0-30 in.Hg, to the hose Apply about 20 in.Hg of vacuum, and wait 20 seconds.
    Fig 4: Identifying Upper Vacuum Hose From Engine Mount Control Solenoid Valve
    G05991733Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Does the engine mount hold vacuum? 

    YES  -Go to step 17.

    NO  -Either the vacuum hose or the engine mount has a vacuum leak. Repair as needed.

  17. Release the vacuum, then apply vacuum again.

    Is there a noticeable change in idle smoothness with and without vacuum applied? 

    YES  -Go to step 18.

    NO  -Replace the front engine mount.

  18. Connect a vacuum pump/gauge, 0-30 in.Hg, to the engine mount control solenoid valve (A).
    Fig 5: Connecting Vacuum Pump/Gauge To Engine Mount Control Solenoid Valve
    G05991734Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there manifold vacuum at idle, and a decrease in manifold vacuum when you raise the engine speed above 1,000 rpm? 

    YES  -The system is OK.

    NO  -Replace the engine mount control solenoid valve.

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